Polydactyly is a condition in which a person has more than five fingers per hand or five toes per foot.

Extra digits; Supernumerary digits

Having an abnormal number of digits (6 or more) can occur on its own, without any other symptoms or disease. Polydactyly may be passed down (inherited) in families. This trait involves only one gene that can cause several variations.

African Americans, more than other ethnic groups, can inherit a 6th finger. In most cases, this is not caused by a genetic disease.

Polydactyly can also occur with some genetic diseases.

Extra digits may be poorly developed and attached by a small stalk (generally on the little finger side of the hand). Or, they may be well-formed and may even function. Poorly formed digits are usually removed. Simply tying a tight string around the stalk can cause it to fall off in time if there are no bones in the digit.

Larger digits may need surgery to be removed. The doctor should ask the parents whether there was polydactyly at birth, because a person may not know they have it.

• Asphyxiating thoracic dystrophy
• Carpenter syndrome
• Ellis-van Creveld syndrome (chondroectodermal dysplasia)
• Familial polydactyly
• Laurence-Moon-Biedl syndrome
• Rubinstein-Taybi syndrome
• Smith-Lemli-Opitz syndrome
• Trisomy 13

Home care may be needed after surgery to remove an extra digit. For example, you will need to check the surgical area to make sure that it is healing correctly and to change the dressing.

This condition is normally discovered at birth and evaluated during the newborn's hospital stay.

The doctor will diagnose the condition based on a family history, medical history, and physical examination.

Medical history questions may include:

• Have any other family members been born with extra fingers or toes?
• Is there a known family history of any of the disorders linked to polydactyly?
• Are there any other symptoms or problems?

Tests used to diagnose the condition:

• Chromosome studies
• Enzymetests
• X-rays
• Metabolic studies

After seeing your health care provider, you may want to add a note to your personal medical record about polydactyly, its diagnosis, and treatment.

During pregnancy, this condition may be diagnosed with ultrasound or a more advanced test called embryofetoscopy during the first three months (trimester).

Review Date: 11/07/2011

Neil K. Kaneshiro, MD, MHA, Clinical Assistant Professor of Pediatrics, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.